For pumping liquids and other fluids, gear pumps have experienced substantial acceptance in the art due to their comparatively small size, quiet operation, reliability, and cleanliness of operation with respect to the fluid being pumped. Gear pumps also are advantageous for pumping fluids while keeping the fluids isolated from the external environment. This latter benefit has been further enhanced with the advent of magnetically coupled pump-drive mechanisms that have eliminated leak-prone hydraulic seals that otherwise would be required around pump-drive shafts.
Gear pumps have been adapted for use in many applications, including applications requiring extremely accurate delivery of a fluid to a point of use. Such applications include, for example, delivery of liquids in medical instrumentation. Another such application is the delivery of coolant liquids to a location where the coolant liquid can be used for active cooling or temperature control of an object.
In many microelectronic devices being produced currently, the relentless demand for increasingly more powerful and faster microprocessors has resulted in the development of microprocessor “chips” that include extremely large numbers (e.g., tens of millions) of active components such as transistors. Since each transistor draws some electrical current, each transistor dissipates some heat. Even though the amount of heat dissipated by a single transistor on a microprocessor chip is miniscule, in a chip that includes millions of transistors, the total heat generated by all the active circuit elements on the chip usually is so great that means must be provided for cooling the chip whenever power is being applied to it; otherwise, accumulated heat could or would destroy the chip. Until very recently, chip cooling has been passive, such as by placing a heat sink in contact with the chip package. In some instances, a heat sink having sufficient heat-removal capacity must be very large relative to the chip, which adds objectionable bulk to the electronic device including the chip. In other instances, using a heat sink that relies solely on passive conduction and convection of heat away from the chip is insufficient for adequate cooling, so a fan must be provided to pass air actively over the heat sink. Very recently, the heat-removal demands of certain microprocessor chips have increased to such an extent that liquid-cooling systems are being developed for cooling the chips. Heretofore, including liquid conduits in spaces occupied by delicate electronics has been avoided at all costs to avoid the catastrophic consequences of leaks. However, the demand for better cooling has forced equipment manufacturers to reconsider this old taboo and to find practical ways of employing liquid cooling while minimizing the probability of leaks and of ameliorating the consequences of leaks.
Other problems that have hindered more widespread employment of liquid cooling of microprocessor chips in microelectronic devices are the extremely tight space constraints that typically exist in such devices and the extremely high reliability specifications that must be met. Liquid cooling requires that liquid conduits and other passageways be provided to the chip, at the chip, and away from the chip. Liquid conduits occupy valuable space and typically provide many ways for liquid to leak from the hydraulic system. Another hindrance has been the additional costs associated with implementing a hydraulic cooling system in a microelectronic device. Yet another hindrance has been the demands on an energy budget posed by the need to run a pump or the like for cooling purposes. These problems can be especially taxing in applications such as lap-top computers in which available interior space and energy budgets are extremely limited.
Ongoing efforts to achieve wider implementation of liquid-cooling in microelectronic devices, especially in devices in which liquid cooling is the only practical option, have stimulated interest in various improvements to hydraulic systems to make these systems suitable for these and other demanding applications. A key focus in these endeavors is the need for smaller, more reliable, and more efficient gear pumps for use in these and other demanding applications.